Rizana Nafeek was beheaded near the Saudi capital Riyadh despite repeated appeals for clemency by Mr Rajapakse as well as international rights group, the foreign ministry said in a statement.

"President Rajapakse and the government deplore the execution of Rizana Nafeek despite all efforts at the highest level of the government and the outcry of the people locally and internationally," the ministry said.

Sri Lankan lawmakers observed a minute's silence during Wednesday's sessions as parliament was told of the execution that was carried out even as Colombo tried to send a delegation to Saudi Arabia to plead for mercy.